1. Field of the Invention
The present invention relates to a terminal device for subscriber telephone interconnection.
Such a device is normally in the form of a box which may be disposed out-of-doors, and therefore subjected to bad weather. Its purpose is to connect the telephone line to one or more subscribers.
2. Related Art
At the present time, boxes of this type exist, particularly in the United States of America, called "Network Interface Devices", which have already come under particular study in that they comprise, in one and the same box, two clearly separate compartments:
a first compartment which is directly accessible when the cover of the box is opened, and which contains the connections for the installation of the subscriber, or subscribers if there is more than one subscriber telephone line connected by this box;
a second compartment which is accessible only if a second cover, generally closed by lead-seal, is opened and which contains the connections for the operator, i.e., the public or private Administration charged with telephonic distribution.
On the subscriber connection side, these modern devices generally use, in addition, a test socket, generally of the "modular jack" type which is placed upstream of the two terminals for connection to the box of the line of the subscriber's installation, and electrically in series therewith.
This test socket is composed, on the one hand, of a female "modular jack" base which is directly connected on the incoming line, at the outlet of the compartment reserved for said Administration, and, on the other hand, of a complementary male socket or plug, also of the "modular jack" type, which is provided at the end of a portion of twin-wire cable, of which the other end is connected to the said two terminals for connection to the interface box of the two wires of the line of the subscriber's private installation. If this male plug is introduced in this female base, continuity of connection is ensured, and this private installation is supplied. It is no longer so if this male plug is withdrawn, but, on the other hand, the subscriber may, in order to test correct functioning of the installation of said Administration in the event of breakdown, directly connect his terminal or telephone set (which is also equipped with a "modular jack" plug) on this female base. If his telephone set then functions normally, the breakdown does not come from the Administration's installation, but from his private installation.
In this type of interconnection box, all the connections are wire connections which present the drawbacks of being long and impractical to install, as well as of being subject to corrosion.
Furthermore, as all the connections are effected by screwing on bared ends of connecting wires, it is easy for a fraud to connect on the line of a subscriber without his noticing, by using such connecting screws. It is also possible to defraud in the same way by using an adaptation with multiple outputs for "modular jack" socket.